Impregnation of leather



United States Patent 3,106,478 IMPREGNATION 0F LEATHER Rodi Heyden and Jurgen Flapper, Dusseldorf, Germany, assignors to Bohme Fettchemie G.m.b.H., Dusseldorf, Germany, a corporation of Germany No Drawing. Filed May 9, 1960, Ser. No. 27,495 Claims priority, application Germany May 14, 1959 9 Claims. (Cl. 106287) This invention relates to the treatment of leather to impart water repellency to the leather. It more particularly relates to a method and composition for impregnating leather to increase the water resistance under mechanical stress.

In a copending application, Serial No. 658,956, now U.S. Patent No. 3,019,133, commonly assigned, is disclosed a process for the impregnation of leather wherein solutions of condensation products formed by alcoholates of polyvalent metals, especially of aluminum, and acid high-molecular weight derivatives of phosphoric acid, especially acid phosphoric acid esters of high-molecular weight organic hydroxyl compounds, in organic solvents are used as impregnating agents. The impregnations impart water-repellent properties as well as water resistance and water impermeability to the leather and are of primary interest in the production of sole leather.

It is an object of our invention to provide a method for imparting a high degree of water repellency to leather.

Another object of our invention is to provide a composition for impregnating leather to impart a high degree of water impermeability to the leather.

A further object of our invention is to provide a method and composition for treating leather to increase the water resistance under mechanical stress.

These and other objects of our invention will become apparent as the description thereof proceeds.

We have now found that the above objects may be attained by the use of our invention. We have found that these impregnating agents of the copending ap lication, Serial No. 658,956, can be substantially improved by using them in conjunction with silicone fluids. A substantial improvement of the so-called dynamic water resistance, i.e., the water resistance under mechanical stress, is obtained thereby. This effect may be further improved by using hard waxes in addition to these two components.

With the silicone fluids alone or the wax impre-gnations alone no really satisfactory improvement of the dynamic water resistance can be achieved. This is also true of the use of the impregnating agents of the copending application, Serial No. 658,956 alone. This effect cannot be achieved except by using, according to the invention, the above described combination of the condensation product with silicone oils, with the addition of waxes for increased improvement. The improvement also makes it possible to reduce the amounts of the impregnating agents normally required according to the eopending application, Serial No. 658,956.

The application of the above-described mixtures to the leather is accomplished in the usual manner, i.e., by spraying, immersion or mechanical application with machines. Favorable concentrations of the impregnating agent mixture solutions in organic solvents are 2 to 15%, preferably 5 to solutions. When applying the agents by spraying with a spray gun, approximately 10% solutions are best, and when applying them by immersion approximately 5% solutions are best. The concentration of impregnating component in these solutions should be about to 50% of the condensation products described "ice in copending application, Serial No. 658,956, about 15 to 50% silicone fluid and about 0 to 30% hard wax.

Suitable solvents are chlorinated hydrocarbons, such as trichloroethylene, perchloroethylene and the like; volatile hydrocarbons, such as petroleum fractions having a boiling point of 50 to 200 C., and also organic solvents, such as methyl ethyl ketone, cyclohexanone, butyl acetic acid ester and the like.

The condensation products used are described in detail in copending application, Serial No. 658,956. They are primarily condensates formed by aluminum isopropylate or aluminum butylate with preferably monoalkyl-phosphoric acid esters having alkyl radicals with at least six carbon atoms. Titanium alcoholates or zirconium alcoholates may also be used in place of the aluminum alcoholates.

The term silicone fluids is primarily intended to include the well-known bifunctional and trifunctional methyl-siloxanes with reactive hydrogen atoms, but also embraces other polymerizates of organosilicon compounds which are characterized by a SiO-Si-- group or also by other linkages, such as fiSi--CH fiSI or -SI-C H Si. The silicon atoms of the silicones may carry organic substituent radicals, such as alkyl, aryl, aralkyl, alkylaryl or alkoxy groups. Of particular interest are those organosilicon polymerizates which contain hydrogen atoms in addition to the organic radicals, such as methyl. These products are commercially available in the form of solutions in organic solvents, such as methylene chloride, which also usually contain catalysts, such as titanic acid tetrabutyl ester.

Suitable hard waxes which may be used as impregnating agents within the scope of the present invention are natural or synthetic wax products, such as paraffin wax, beeswax, carnauba wax and especialy montan wax or ester waxes and carbonamide waxes of a synthetic nature. The various components may be dissolved without difliculties in the solutions described in the copending application, Serial No. 658,956.

While the type of solvent is relatively immaterial when using the immersion method, only those solvent mixtures which contain high-boiling-point components, such as heavy petroleum fractions, toluene or xylene, are suitable for impregnation of the leather by the spray method. By addition of small amounts of mineral oil to the spray mixture the impregnating agent can be caused to penetrate into the leather rather than adhere to the surface of the leather. Low-boiling-point solvents are unsuitable in this case because they evaporate too rapidly upon spraying of the diluted impregnating agent, so that the impregnating agent settles primarily on the surface of the leather. In the immersion method the distribution of the impregnating agent in the leather may also be regulated by changing the content of high-boiling-point solvents.

The impregnating agents according to the invention may be used in conjunction with all types of leather and are particularly suited for the preparation of pastel-colored or White suede or grained leather, especially upper leather.

The following specific examples are given to illustrate our invention and to enable persons skilled in the art to better understand and practice the invention and are not intended to be limitative. The silicone fluid used in EX- amples I-lV was a 50% solution of siloxane in perchloro ethylene.

Example I 20 parts by weight of a solution of a condensation product, formed from 204 parts aluminium isopropylate and 144 parts by weight monoalkyl phosphoric acid ester (alkyl radicals O -C in 500 parts by weight trichloroethylene were diluted with 30 parts by weight trichloroethylene and the solution was then admixed with 50 parts by weight of a solution consisting of 5 parts montan wax, 7.5 parts silicone fiuid (commercial silicone WS 60) and 110 parts trichloroethylene. The finished solution contained about 12% of impregnating components. The solution was used for impregnating chrome-tanned leather by immersion, whereby excellent dynamic water resistance effects were obtained.

Example 11 2.5% montan wax and 3.7% silicone fluid were dissolved in 70 parts of a heavy petroleum fraction (boiling point 140 to 200 C.). The resulting solution was admixed with 20 parts of the solution of the condensation product of aluminum propylate and a monoalkyl phosphoric acid ester mixture described in Example I. This impregnating agent was particularly suitable for application on chrome-tanned leather and was applied by spraying. After drying and storing the treated leather for a few days, it was tested in a Maeser machine.

Water Water Absorption Penetration After- Amount oi Begun Water let After Through Number 10,000 20,000 After 10,000 of Bends Bends, Bends, Bends, g. percent percent Untreated Leather 1,200 7. 8 14. 8 0.17 Treated Leather More 5. 3 8. 4

than 50,000

Example Ill Aniline-dyed calf leather was immersed for minutes into the trichloroethylene solutions of the following impregnating agents:

A test of these leather impregnations produced the following values:

Water began to pass through after number of beads Untreated leather 600 Impregnated with:

Solution A Above 100,000 Solution B Above 100,000 Solution C 18,500 Solution D 85,000

The following were used as comparative impregnations: Silicone fluid alone (5% solution) 500 Montan wax alone (5% solution) 150 Example IV Chrome-tanned, aniline-dyed apparel leather was immersed for 5 minutes into 5% trichloroethylene solutions of the following impregnating agents:

A. Silicone fluid (100%). B. Impregnating agent according to Example I above.

4 After drying and storing the treated leather for a few days, the following impregnation effects were obtained:

While we have set forth certain specific embodiments and preferred modes of practice of our invention, it will be understood that the invention is not limited thereto and that various changes and modifications may be made in the invention without departing from the spirit of the disclosure and the scope of the appended claims.

We claim:

1. A process for treating leather to impart water repellency thereto which comprises impregnating the leather with a 2 to 15% organic solvent solution of a composition comprising (a) from about 15 to 50% of a product formed by (1) alcoholates of metals selected from the group consisting of aluminum, titanium and zirconium, and (2) monoalkyl phosphoric acid esters having from about 6 to 26 carbon atoms in the alkyl radical, (b) from about 15 to 50% of polysiloxanes substituted at the silicon atom with substituents selected from the group consisting of hydrogen, alkyl radicals and aryl radicals, and (c) from about 0 to 30% hard waxes which are solids at ambient temperatures, the recited element of said composition being the sole elements to impart water repellency.

2. The process of claim 1 wherein the treating solution contains starting materials for the condensation product in place of the final condensation product.

3. A process for treating leather to impart water repellency thereto which comprises impregnating the leather with a leather oil containing a solution comprising a 2 to 15 organic solvent solution of a composition comprising (a) from about 15 to 50% of a product formed by (l) alcoholates of metals selected from the group consisting of aluminum, titanium, and zirconium, and (2) monoalkyl phosphoric acid esters having from about 6 to 26 carbon atoms in the alkyl radical, (b) from about 15 to 50% of polysiloxanes substituted at the silicon atom with substitutents selected from the group consisting of hydrogen, alkyl radicals and aryl radicals, and (c) from about 0 to 30% hard waxes which are solids at ambient temperatures, the recited elements of said composition being the sole elements to impart water repellency.

4. A process for treating leather to impart water repellency thereto which comprises impregnating the leather with a 5 to 10% organic solvent solution of a composition comprising (a) from about 15 to 50% of a product formed by (1) alcoholates of metals selected from the group consisting of aluminum, titanium and zirconium, and (2) monoalkyl phosphoric acid esters having from about 6 to 26 carbon atoms in the alkyl radical, (b) from about 15 to 50% of polysiloxanes substituted at the silicon atom with substituents selected from the group con sisting of hydrogen, alkyl radicals and aryl radicals, and (c) from about 0 to 30% hard waxes which are solids at ambient temperatures, the recited elements of said composition being the sole elements to impart water repellency.

5. A composition for treating leather to impart water repellency thereto which comprises 2 to 15% organic solvent solution of (a) from about 15 to 50% of a product formed by 1) alcoholates of metals selected from the group consisting of aluminum, titanium and zirconium, and (2) monoalkyl phosphoric acid esters having from about 6 to 26 carbon atoms in the alkyl radical, (b) from about 15 to 50% of polysiloxanes substituted at the silicon atom with substituents selected from the group consisting of hydrogen, alkyl radicals and aryl radicals, and (c) from about to 30% hard waxes which are solids at ambient temperatures, the recited elements of said composition being the sole elements to impart water repellency.

6. The composition of claim wherein the condensation product is replaced by the starting materials used to produce said product.

7. A composition for treating leather to impart water repellency thereto which comprises a leather oil containing a solution comprising 2 to 15% organic solvent solution of (a) from about 15 to 50% of a product formed by (1) alcoholates of metals selected from the group consisting of aluminum, titanium and zirconium, and (2) monoalkyl phosphoric acid esters having from about 6 to 26 carbon atoms in the alkyl radical, (b) from about 15 to- 50% of polysiloxanes substituted at the silicon atom with substituents selected from the group consisting of hydrogen, alkyl radicals and aryl radicals, and (c) from about 0 to 30% hard Waxes which are solids at ambient temperatures, the recited elements of said composition being the sole elements to impart water repellency.

8. A composition for treating leather to impart water repellency thereto which comprises 5 to 10% organic solvent solution of (a) from about 15 to 50% of a product formed by (1) alcoholates of metals selected from the group consisting of aluminum, titanium and Zirconium, and (2) monoalkyl phosphoric acid esters having from about 6 to 26 carbon atoms in the alkyl radical, (b) from about 15 to 50% of polysiloxanes substituted at the silicon atom with substituents selected from the group consisting of hydrogen, alkyl radicals and aryl radicals, and (c) from about 0 to 30% hard waxes which are solids at ambient temperatures, the recited elements of said composition being the sole elements to impart water repellency.

9. A leather product produced by the method of claim 1.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,879 Currie Sept. 28, 1954 2,728,736 Hunter et a1. Dec. 27, 1955 2,772,988 Plapper et a1. Dec. 4, 1956 2,801,190 Orthner et a1 July 30, 1957 2,884,393 Gilkey Apr. 28, 1959 2,970,976 Leclercq et al. Feb. 7, 1961 2,977,249 Heyden et al Mar. 28, 1961 3,038,818 Findlay June 12, 1962 

5. A COMPOSITION FOR TREATING LEATHER TO IMPART WATER REPELLENCY THERETO WHICH COMPRISES 2 TO 15% ORGANIC SOLVENT SOLUTION OF (A) FROM ABOUT 15 TO 50% OF A PRODUCT FORMED BY (1) ALCOHOLATES OF METALS SELECTED FROM THE GROUP CONSISTING OF ALUMINUM, TITANIUM AND ZIRCONIUM, AND (2) MONOALKYL PHOSPHERIC ACID ESTERS HAVING FROM ABOUT 6 TO 26 CARBON ATOMS IN ALKYL RADICAL, (B) FROM ABOUT 15 TO 50% OF POLYSILOXANES SUBSTITUTED AT THE SILICON ATOM WITH SUBSTITUENTS SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, ALKYL RADICALS AND ARYL RADICALS, AND (C) FROM ABOUT 0 TO 30% HARD WAXES WHICH ARE SOLIDS AT AMBIENT TEMPERATURES, THE RECITED ELEMENTS OF SAID COMPOSITION BEING THE SOLE ELEMENTS TO IMPART WATER REPELLENCY. 